*{
    padding: 0px;
    margin: 0px;
}


.mask{
    height: 100%;
    width: 100%;
    opacity:0.5; 
    background: #000;
    position:absolute; 
    left:0; 
    top:0; 
    display:block;
}

#demo01{

   position:absolute; 
    left:0; 
    top:0; 
    width: 100px;
    height: 100px;
        
    display: none;
}

#searchTip{ 
    width:980px; 
    height:800px; 
    position: absolute; 
    left:50%; 
    margin-left: -490px; /*让searchTip处于居中位置*/
    display:none;
}